Inert gas absorption refrigerator



Dec. 27, 1955 G. A. GRUBB 2,728,202

INERT GAS ABSORPTION REFRIGERATOR Filed. Oct. 20, 1951 5 Sheets-Sheet lW 79 ff J? /g x. V IN V TOR. wi {22/ M Dec. 27, 1955 G. A. GR'UBB2,728,202

INERT GAS ABSORPTION REFRIGERATOR Filed on. 20, 1951 5 sheetssheet 2 BI, W

Dec. 27, 1955 cs. A. GRUBB 2,728,202

INERT GAS ABSORPTION REFRIGERATOR Filed Oct. 20, 1951 5 Sheets-Sheet 3Ulflllfi E INERT GAS ABsonPrioN REFRIGERATOR Gunnar Axel Grubb, Bromrna,Sweden, assignor to Aktiebolaget Elektrolux, Stockholm, Sweden, acorporation of Sweden My invention relates to absorption refrigerationsystems of the inert gas type, and more particularly relates to such arefrigeration system having plural temperature evaporator structure.

It is an object of my invention to provide an improved evaporatorstructure in which several cooling elements operable at differenttemperatures may be effectively employed to cool the thermally insulatedinterior of a refrigerator cabinet and a freezing section disposedtherein. I accomplish this by providing an inert gas circuit having lowand higher temperature evaporators which are formed of piping anddisposed at substantially the same level in the interior of arefrigerator, the low temperature evaporator providing a freezingsection having a plate-like supporting surface and piping associatedtherewith, and the higher temperature evaporator providing an aircooling section including piping having a relatively extensive heattransfer surface. In a preferred embodiment the freezer and air coolingsections are disposed alongside one another and together occupy a majorportion of the space across the cabinet interior at the front accessopening thereof.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the claims. The invention, both asto organization and method, together with the above and other objectsand advantages thereof, will be better understood by reference to thefollowing description taken in connection with the accompanying drawingsforming a part of this specification, and of which:

Fig. 1 is a fragmentary front view of a refrigerator embodying theinvention;

Fig. 2 is a horizontal sectional view of the refrigerator shown in Fig.l to illustrate details more clearly;

Fig. 3 illustrates more or less diagrammatically the type ofrefrigeration system with which the parts shown in Figs. 1 and 2 areassociated; and

Figs. 4 and 5 are views similar to Fig. 2 illustrating other embodimentsof the invention.

Referring to Figs. 1 and 2, a household refrigerator is provided with alow temperature freezing section 11 which is disposed in a highertemperature food storage space 12. The freezing section 11 and storagespace 12 are arranged to be cooled by a plurality of evaporators orcooling elements 14, 15 and 16 which are operable at different averageor mean temperatures. The evaporators 14, 15 and 16 form part of anabsorption refrigeration system of the inert gas type and are usuallyinserted into the storage space 12 at the rear of the refrigerator inany suitable manner, such as, for example, through an opening in therear insulated wall which is adapted to be closed by an insulatedclosure member 17. A refrigeration system of this type is more or lessdiagrammatically shown in Fig. 3 in which the evaporators 14, 15 and 16are illustrated apart from a household refrigerator.

The system illustrated is of a uniform pressure type atentO ice j Iemploying an inert gas or pressure equalizing agent. In

U Fig. 3 a refrigerant fluid, such as liquid ammonia, for

example, is introduced through a conduit 18, 'into the evaporators 16,15 and 14. The refrigerant fluid in the evaporators or cooling elementsevaporates and diffusesinto an inert gas, such as hydrogen, for example,to produce a refrigerating effect and abstract heat from thesurroundings. The rich gas mixture of refrigerant vapor .-gas heatexchanger 20, conduit 21 and absorber vessel 22 into the lower end of anabsorber coil 23. In absorber coil 23 the rich gas mixture flowscounter-current to downwardly flowing absorption liquid which entersthrough a conduit 24. The absorption liquid absorbs refrigerant vaporfrom inert gas, and inert gas weak in refrigerant flows from absorbercoil 23 in a path of flow including a conduit 25, another passage of gasheat ex-- changer 20 and a conduit 26 which is connected to one:

end of the evaporator or cooling element 14.

The circulation of gas in the gas circuit just described. is due to thedifference in specific weight of the columns.- of gas rich and weak,respectively, in refrigerant vapor... Since the column of gas rich inrefrigerant vapor and.

flowing from the upper end of evaporator 16 to the absorber coil 23 isheavier than the column of gas weak in refrigerant and flowing from suchcoil to the evaporators 14, 15 and 16, a force is produced or developedwithin the system for causing circulation of inert gas in the mannerdescribed.

From the vessel 22 enriched absorption liquid flows through a conduit 27and an inner passage 28 of a liquid' heat exchanger 29 into the lowerend of a vapor lift pump 30 of a generator unit 31. The generator unit31 comprises a heating tube 32 having the vapor lift pump 30 and aboiler pipe 33 in thermal exchange relation therewith, as by welding,for example. By heating generator unit 31, as by an electrical heatingelement within the lower part of heating tube 32 or by a fiuid fuelburner, for example, liquid from the inner passage 28 of the liquid heatexchanger is raised by vapor lift action through pump 30 into the upperpart of the boiler pipe 33. The liberated refrigerant vapor enteringboiler pipe 33 through the pump 30, and also vapor expelled fromsolution in the boiler pipe, flows upwardly into an air cooled condenser34 provided with a plurality of cooling fins 35.

Refrigerant vapor is liquefied in the condenser 34 and returned to theevaporators 14, 15 and 16 through the conduit 18 to complete therefrigerating cycle. Gravity flow of liquid refrigerant is effectedthrough the evaporators, the evaporator 14 receiving liquid refrigerantfrom the upper evaporators 15 and 16. The outlet end of condenser 34 isconnected by a conduit 36 to the gas circuit, as to the gas heatexchanger 20, for example, so that any non-condensable gas that may passinto the condenser will flow to the gas circuit and not be trapped inthe condenser. The weakened absorption liquid, from which refrigerantvapor has been expelled, is conducted from boiler pipe 33 through aconduit 37, the outer passage 38 of the liquid heat exchanger 29 andconduit 24 into the upper part of absorber coil 23.

It Will be understood that the evaporators 14, 15 and 16 in Fig. 3 arediagrammatically shown in their relation to other parts of the system,and that in Figs. 1 and 2 a practical form of the evaporator structurein accord with the invention isillustrated in which the evaporator 14comprises a horizontally disposed coil located essentially in a singlehorizontal plane, and evaporator 15 also comprises a horizontallydisposed coil located essentially in a single horizontal plane which isslightly above the horizontal plane of the evaporator 14 but essentiallyat Patented Dec. 27, 1955.

3. the same level in the interior of the refrigerator cabinet. Theevaporator 16 comprises horizontally disposed piping positionedsubstantially at or slightly above the horizontal plane of evaporator15.. The evaporators 14, 15 and 16 arev connectedin series relation,and, while all of the conduit connections associated with the coils andpip ing .may notbe immediately evident in Figs. 1 and 2, it is to beunderstood that such connections are generally like thosediagrammatically shown in Fig. 3.

Accordingly, flow of iiuids takes place in Figs. l and 2 in the mannershown in Fig. 3, whereby inert gas Weak in refrigerant flows from theabsorber 23 through the conduit 25 to one passage of the gas heatexchanger 20 which is embedded in the insulated closure member 17 in therear wall 39of the cabinet. end of such gas heat exchanger passage weakinert gas flows through conduit 26 to one end of the horizontalevaporator coil14. As best shown in Fig. l, inert gas emerging fromevaporator coil 14 passes through an upwardlyinclined connection 4%)into the horizontal evaporator coil 15 and thence through the evaporatorpiping 16 which is connected by conduit 19 to one end of the otherpassage of the gas heat exchanger 26, the opposite end of which isconnected by the conduit 21 to the lower end of the absorber coil in themanner shown in Fig. 3.

Liquid refrigerant formed in condenser 34 flows therefrom throughconduit 18 which is connected to the end region of evaporator piping 16at 11, as best seen in Fig. 2. Hence, in Fig. 2 liquid refrigerantinitially passes from left to right in evaporator piping 16. Therefrigerant then passes through evaporator coil 15 and finally flowsthrough evaporator coil 14. With this arrangement liquid refrigerantflows in the presence of and in counterfiow to inert gas in theevaporator piping 16 and both of the horizontal evaporator coils 14and15. In order to obtain good distribution of liquid refrigerant in theevaporator structure and promote evaporation and diffusion ofrefrigerant fluid into the inert gas, the piping and coils may beprovided with suitable inserts, such as fine wire coils or screens, forexample.

Since the inert gas flows successively through the evaporators 14,15 and16, the gas in the horizontal evaporator coil 14 contains a lesseramount of refrigerant vapor than the gas in the evaporator coil 15 andevaporator piping 16. The partial vapor pressure of the refrigerant is agradient, so that the temperature of liquid refrigerant in theevaporator coils and piping also is a gradient, the evaporatingtemperature of liquid being lowest in the horizontal evaporator coil 14which constitutes the freezing portion of the evaporator structure.

The refrigerating eifect produced by the horizontal evaporator coil 14,which is adapted to be operated at temperatures below freezing, isprirnarily adapted to effect cooling of the freezing section 11. Asshown in Fig. l, the freezing section 11 comprises a shell 42 formedwith a front access opening adapted to be closed by a cover plate orclosure member (not shown) hinged to the shell in any suitable manner. Ashelf or plate-like member 43 is provided within shell 42 to theunderside of which is heat conductively connected the horizontalevaporator coil 14. A body of suitable insulation 44 is retained at theunderside of shelf 43, so that evaporator coil 14 will eflicientlytransmit cooling effect to matter placed on the shelf, such as trays 45containing water to be frozen, for example, and also prevent air in thestorage space 12 from coming in direct contact with evaporator coil 14.The top 46 of the freezing section 11 is closely adjacent to the ceilingor roof of the storage space 12.

In the preferred embodiment illustrated, the horizontal evaporator coil15 is located alongside the freezing section 11. In order to provide arelatively extensive heat transfer surface, a number of verticallyextending heat transfer membersor fins 47 are fixed to the horizontallyextendin'g arm's of; the coil 15. The refrigerating effect produced. bythehorizontal evaporator coil 15, whichis From the opposite 7 adapted tobe operated at a higher temperature than that of evaporator coil 14, anddesirably above freezing, is primarily utilized to cool air in thestorage space 12, the relatively extensive heat transfer surfaceprovided by the fins 47 promoting such air cooling. The inert gasleaving the horizontal evaporator coil 15 is relatively rich inrefrigerant vapor. However, such enrichedinert gas often may be employedto effect additional cooling and, as shown in Fig. 2, the rich inert gaspasses from evaporator coil 15 into auxiliary evaporator piping 16 inwhich liquid refrigerant evaporates and diffuses into the rich inertgas.

It has already been pointed out that liquid refrigerant flowssuccessively through evaporators 16, 15 and 14, respectively. Since thepartial pressure of refrigerant vapor in the gas mixture in theevaporator piping 16 is less than the vapor pressure of the warm liquidrefrigerant entering piping 15 through conduit 18, liquid refrigerantevaporates and diffuses into the gas mixture with conse quent absorptionof heat from liquid refrigerant in thQz.

evaporator piping 16. Hence, the highest temperature evaporator piping16 not only functions to abstract heat from air in storage sp ce 12 butalso effectively-servesas.

a precooler for liquid refrigerant. Such precoolcd liquid refrigerantsubsequently flows to the horizontal evapo' rator coil 14 into thepresence of inert gas which is weakest in refrigerant vapor, wherebyeffective low temperaturecooling below the freezing temperature iseffected in the freezing section 11. Since liquid refrigerant entering.the-- evaporator coils 14 and 15 from the evaporator coil piping, 16flows by gravity through such piping and both coils, it

is desirable to arrange successive straight portions and turns in-thedirection of liquid how in such a mannerthat gravity flow of the liquidis promoted from the region-41- to a lower region at which conduit 26 isconnected to-one end of evaporator coil 14.

It will now be understood that evaporator structureof the horizontallyextending type has been provided-inFigst 1 and 2 which takes up aminimum amount of usable space in the storage compartment or space 12.The freezing section 11 and higher temperature cooling elements: 15 and16 are essentially located at the'sarne level adjacent the ceiling ofthe storage space 12, the freezingsection-Lh. and higher temperaturesection 15 being disposed'side by.

side and together extending entirely across the storage space 12 fromone lateral side 48 to the opposite lateralz.

side 48 of the refrigerator 1%). The freezingsectionll may occupy fromone-fourth to three-fourths of the total width of the storage space, theshelf 43 preferably being dimensioned so that a definite number ofconventional trays 45 for producing ice cubes can be placed thereonalongside one another and occupy substantially the entire area of thesupporting shelf. The freezing section 11 desirably should be of minimumoverall height, the top.

wall thereof preferably being located at the immediate vicinity of andessentially in the same horizontal plane asu.

the ceiling or top wall49 of the storage space 12 of the refrigerator.

such arrangement an adequate liquid head must be provided in therefrigerant supply line 18 leading downward from the condenser 34.

As diagrammatically shown in Fig. 2, the generator unit 31, absorber 23and condenser 34 are disposed in aver: tically extending apparatuscompartment 50 at the rean;

Upward circulation of air is-in of the refrigerator 10. duced by naturaldraft in the compartment 50 whichdefines a vertically extending fine,and such upward movement of air eifects cooling of the absorber 23 atone level.

and the condenser 34 located at a higher level. The

straight portions of the condenser coil 34 aredisposed; essentially inthe same horizontal plane or in a planeat a slight angle to thehorizontal, such plane being atLa level closely adjacent to the topexterior wall ofthe refrigerator 10. With such disposition of thecondenser 34 relative to the evaporator structure in storage space 12, avertically extending path of flow for refrigerant is provided by conduit18, whereby an adequate liquid head will be assured to promote gravityflow of liquid refrigerant through all of the evaporators or coolingelements 14, and 16. However, the heat dissipating members or coolingfins of the condenser 34 can extend vertically downward in the flue 50 adistance well beneath the horizontal plane of the evaporator coil 14.

The higher temperature evaporator coil 15 and heat transfer fins 47fixed thereto desirably are distributed over a cross-sectional area ofstorage space 12 which is at least half of the cross-sectional area ofthe freezing section 11 and may be equal to the cross-sectional area ofthe latter. Further, the bundle of fins 47 is formed in such a mannerthat air circulating in space 12 can pass both in an upward and downwarddirection through the gaps in the bundle of fins. In certain instancesit may be desirable to provide a small vertically extending gap betweenthe top wall 49 and bundle of fins 47 which is at least as great as thedistance between adjacent fins 47.

Since the bottoms of the freezer and air-cooling units are essentiallyat the same height, as best seen in Fig. l, the region below these unitsprovides an unobstructed compartment 12 which extends downwardlysubstantially at the same level from all regions of the bottoms of boththe freezer unit 11 and air-cooling unit which includes the fins 47. Thecompartment 12 provided in this manner is of maximum cross-sectionalarea, and the same as that of the storage space defined by the innerliner of the cabinet, at successively lower levels through a verticaldistance extending downwardly from the bottoms of both of the freezerand air-cooling units to the bottom of the storage space. Hence, thecompartment 12 forms the only zone having such maximum cross-sectionalarea throughout substantially its entire height which is at a highertemperature than that prevailing in the freezer unit 11.

As previously explained, the evaporator piping 16 may be employed as anauxiliary high temperature cooling element in which evaporation ofliquid refrigerant takes place in the presence of rich inert gas. Asseen in Fig. 2, such auxiliary evaporator may be formed of a single tlength of piping which is provided with heat transfer fins 51 anddisposed closely adjacent to the rear wall 3d at the rear of theevaporator coils 14 and 15.

In certain instances it may be preferable only to circulate relativelycool rich inert gas through the piping l6 and to initially supply liquidrefrigerant to the evaporator coil 15, thus shifting the connection ofconduit 18 from the region 41 to the region indicated at 52 in Fig. 2.Such a modification is illustrated in Fig. 4 in which parts similar tothose shown in Figs. 1 and 2 and described above are referred to by thesame reference numerals. In Fig. 4 the evaporator coil 14a having asingle U-shaped loop is associated with a freezing section 11:: capableof accommodating a single tray for producing ice cubes. The highertemperature evaporator coil 15a comprises a single U-shaped loop havingheat transfer fins 47a fixed thereto. However, it will be evident thatthe evaporator coils 14a and 15a may each comprise several U-shapedloops and connecting bends to provide an evaporator structure whichextends up to three-fourths of the total width of the storage space 12.This arrangement provides a space at one side of the evaporatorstructure which extends downwardly from the top wall 49 of the storagespace 12 to the position of the highest located shelf (not shown), sothat tall items like bottles, for example, can be conveniently stored inthe refrigerator.

in the embodiment of Fig. 4, the gas heat exchanger is provided byarranging the conduit 250, through which weak inert gas fiows fromabsorber 23 to evaporator coil 14a, in heat conductive relation withconduit 1911 through which rich inert gas flows from evaporator coil 15ato supply line 18a conducts refrigerant from condenser 34 to evaporatorcoil 15a at the region 32a.

Fig. 5 illustrates a further modification in which the low temperatureevaporator coil 14b is associated with a freezing section 11b in thesame manner as in Fig. 4. However, in Fig. 5 only a part of the highertemperature evaporator coil 15b is positioned alongside of the freezingsection 11b while another part thereof occupies the space between therear of the freezing section and the rear wall 39 of the refrigerator.This arrangement is particularly advantageous in household refrigeratorsof small size, because the ice cube trays in small size refrigeratorsgenerally are of such length that the freezing section terminates at aregion removed from the rear wall 39 of the refrigerator. By locatingpart of the higher temperature evaporator coil 15b at the rear of thefreezing section lib, space which otherwise would not be used iseffectively employed to effect space cooling. In each of the embodimentsillustrated and described, it will be seen that the freezing section andhigher temperature air cooling section are located substantially at thesame level in the cabinet interior and together occupy a major portionof the space extending from one lateral side wall to the oppositelateral side wall of the cabinet interior.

Modifications of the embodiments of my invention which I have describedwill occur to those skilled in the art. Therefore, I intend in theclaims to cover all those modifications which do not depart from thespirit and scope of the invention.

What is claimed is:

l. A refrigerator including a cabinet having thermally insulated top,bottom, rear and lateral side walls defining a single thermallyinsulated storage space and an absorption refrigeration systemassociated therewith having a circuit for inert gas including pipingforming low and higher temperature evaporator sections in which refrigerant fluid evaporates in the pesence of inert gas, conduit means in saidcircuit including said piping for eifecting circulation of inert gassolely by the difference in specific Weight of columns of gas rich andweak, respectively, in refrigerant vapor, a freezer unit in the storagespace comprising wall meansto provide a compartment substantiallysegregated from the rest of the storage space to restrict circulation ofair therebetween, the piping of said low temperature evaporator sectionbeing in thermal ex change relation with saidv wall means which providesa supporting surface for matter to be refrigerated, an air cooling unitin the storage space comprising means providing a relatively extensiveheat transfer surface and the piping forming said higher temperatureevaporator section which is in thermal exchange relation therewith,

said freezer and air cooling units, including all of said piping in thestorage space forming a part of said units, being disposed in side byside relation between the lateral side walls of the cabinet, saidfreezer unit including a top horizontal wall part formed by said Wallmeans which is essentially in the same horizontal plane as the ceilingof the storage space, means including said piping for flowingrefrigerant fluid in the storage space in the presence of inert gas in avertically extending path of flow which is in a vertical range entirelybetween the top and bottorn, respectively, of said air-cooling unit, theregionv below said freezer and air-cooling units providing anunobstructed compartment which extends downwardly substantially at thesame level from all regions of the bottoms of both of said units, andsaid compartment always having a maximum cross-sectional area, which isthe same as that of the storage space, at successively lower levelsthrough a vertical distance extending downwardly from the bottoms ofboth of said units to the bottom of the storage space, said compartmentforming the only zone having such cross-sectional area throughoutsubstantially its entire height which is at a higher temperature thanthat prevailing in said freezer unit.

2J.A" refrigerator including a cabinet having thermally insulated'top,b'ottom, rear and lateral side walls defining a single thermallyinsulated storage space and an absorption refrigeration systemassociated therewith having a circuitfor inert gas includingpipingforming low and higher temperature evaporator sections in whichrefrigerantfiuidevaporates in the presence-of. the inert gas,conduitmeans insaid circuit including said piping for effect ingcirculation of the inert gas solely by the difference inspecific'weightof columns of 'gas rich and weak, respectively, inrefrigerant'vapor, a freezer unit in the storage space'comprising wallmeans to provide a compartment substantially segregated from the rest ofthe storage space to'restri'ct circulation'of air therebetween, thepiping of said low temperature evaporatorsection being in thermalexchange relation'with said wall'm'eans which provides asupporting'surface for matter to be refrigerated, an air cooling unitinthe storage space comprising means providing a relatively extensiveheat transfer surface and thexpipingformingsaid higher temperatureevaporator section which is in thermal exchange relation therewith, saidfreezer and'air-eooling units, including all of said piping forming apart of said units, being disposed in sideby-side relation and occupyinga major portion of the entire space between-the lateral side walls ofthe cabinet, said freezer unit being spaced from the rear wall of thecabinet with the top parts of both of said units being located at theimmediate vicinity of and closely adjacent to their ceiling of thestorage space, said air-cooling unit including a first portion inside-by-siderelation with said freezer unit between the lateral sidewalls and a second portion in'the space between the rear of said freezerunit and tlie rear wall of the cabinet, means including said piping forflowing refrigerant fluid in said storage space in'the presence of theinert gas in a vertically extending path-of flowwhich is in a verticalrange entirely between the top and bottom, respectively, of saidair-cooling unit, the region below said freezer and air-cooling unitsproviding an'unobstructed food storage compartment which extendsdownwardly at substantially the same level from all regions of thebottoms of both of said units, said food storage compartmentconstituting the only part of said single storage spaceavailable forstoring food in a zone which is at a higher temperature than thatprevailing in said freezer unit.

3. A refrigerator including a cabinet having thermally insulated top,bottom, rear and lateral side walls defining a singlerthermallyinsulated storage space and an absorption refrigeration systemassociated therewith having a circuit for inert gas including piping insaid storage space forming low and higher temperature evaporatorsections in which refrigerant fluid evaporates in the presence of thegas, conduit means in saidcircuit including said piping for effectingcirculation of inert gas solely by the dif-- ated, an air cooling unitin the storage space comprising means providing a relatively extensiveheat transfer surface and the piping forming said higher temperatureevaporator section which is in heat exchange relation therewith, andsaid freezer and air cooling units, including all of the piping in thestorage space forming a part of said units, being disposedin sideby siderelation be tween the lateral side walls of the cabinet, said freezerunit including a top horizontal wall formed by said wall means which isessentially in the samehorizontal plane as the ceiling of the storagespace, means including said piping for flowing refrigerant fluid in thestorage space in the presence of inert gas in a vertically extendingpath of flow which is in a vertical range entirely between the top andbottom, respectively, of said air-cooling unit, the region below saidfreezer and air-cooling units providing an unobstructed compartmentwhich extends downwardly substantially at the same level from allregions of the bottoms of both of said units, and said compartmentalways having a maximum cross-sectional area, whichis the same as thatof the storage space, at successively lower levels through a verticaldistance extending downwardly from the bottoms of both of said units tothe bottom of the storage space, said compartment forming the only zonehaving such cross-sectional area throughout substantially its entireheight which is at a highertemperature than that prevailing in saidfreezer unit.

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